Creating a new DP tool for designing the EPR

28 February 1998

When Germany and France decided to jointly develop a next generation reactor plant, known as the European PWR – the EPR, Siemens KWU and Framatome, and their subsidiary NPI, had to create a common design that satisfied the demands of both countries as well as the international marketplace. To face the many challenges, the project took advantage of the evolution in computer technology that has occured since the last generation of reactors was designed, to develop an advanced integrated data processing (DP) tool to meet the needs of this complex and long-term design programme.

Computers were already essential tools in the design and construction of earlier KWU nuclear power stations. A hiatus of several years in the construction of new nuclear power stations in Germany meant, however, that the evolution in computer technology had passed by the DP tools that it had used for designing nuclear plant. When Electricité de France (EDF) and nine major German utilities decided to co-operate in the EPR project, KWU was directly confronted with the question of the availability and fitness of the DP design and engineering tools used for its Konvoi series of nuclear plants. As an analysis has shown that it would be neither advisable nor commercially viable to import existing software into the new DP landscape, the only alternative was to make a fresh start, taking full advantage of the substantial improvements in the technology.

In order to provide optimum process support during the development of the reactor and to utilise all possibilities of DP integration (eg workstation and PC), a number of innovative goals were defined for the development of a powerful planning tool. The modelling of these objectives in the software was also intended to ensure KWU’s continued ability to build turnkey nuclear power stations.

The primary aims of the current development work are to utilise the computer potential for productivity improvements and to maintain know-how being generated by the project. This is to be achieved through an integrated DP tool which could be used by all the various engineering disciplines involved, from design engineering, through implementation, to the operation of large-scale plant.

The EPR as a whole includes an estimated 300 000 parts, many of them interlinked. If the data involved is to remain manageable, then redundant storage of data is to be avoided. To further illustrate the volume of data that must be handled, current estimates put the size of the EPR buildings at 850 000 m3, housing 17 000 pipe segments with a length of 150000 m and 30000 mountings, 3000 pipe catalogue components, 20 000 valves, 1000 items of process-engineering equipment and aggregates and 5000 electricity consumers.

All activities must therefore be based on a central data pool whose content always reflects the current status of the project as a whole. Centralisation of plant data requires a high degree of co-ordination of planning methods and procedures in the departments using the system and thus facilitates the use of process-orientated procedures. Furthermore, it is planned that the logical checks of manual data input and the enforced adherence to rules and standards will automate and simplify project documentation for the sub-sectors concerned, improve QA and significantly reduce costs by allowing more efficient processing.

Once the plant is operational, it is planned that actual data from the central data pool will form the basis of an operations management system. A subsequent inventory of the plant, as has been made in the past, will no longer be necessary.

The division of DP tool development between the project partners, Siemens KWU and Framatome, also presented a special challenge, requiring:

• Agreement on technical definitions and terms.

• The use of the same software tools at both companies.

• The use of standardised layout for drawings, lists and data sheets.

• Regular exchange of data between Germany and France (controlled access to each others’ data).

PLANNING THE DP LANDSCAPE

As a result of the conditions and requirements described above, it was necessary to take certain technical decisions and make available a number of DP tools before starting work on the first engineering phase of the EPR project (the basic design) which was completed in the Summer of 1997.

Illustration of the entire plant as a logical data structure (plant data model)

The basis of the engineering project is the structuring of the plant and the technical definition of the plant parts (classification). For this, the plant is pictured in the form of a logical data structure. This specifies, for example, that a process-engineering system (eg the primary or secondary system) is made up of pipes, valves, pumps, heat exchangers and connecting pieces with the appropriate technical data in each case. In DP terms these are “objects” and “attributes”. This structure is made up of object classes (eg pipes, pumps, rooms), attributes (eg designation, pipe diameter, delivery head, room number) and the relationship between object classes (eg pipe to pump, pump in room).

The plant structure is stored in a database as a so-called meta-model, as specific rules, from which the central data pool is then configured. Access to the central data pool is by means of a generic application (ie the frames are generated dynamically after the configuration of the database), so that the software itself does not have to be adapted following a change or extension to the plant structure.

Producing the system circuit plans

As the first step in engineering development, the process-engineering system plans are produced using a 2D CAD program which works with standardised mechanical symbols and uses initial plausibility checks. To avoid duplicating entries in the project it is necessary that the CAD program should as far as possible recognise not only alphanumeric data but also logical connections, such as the allocation “pipe connects to pump” or “pump belongs to design section”, so that they can then be entered in the central data pool.

Process and equipment data-base (central data pool)

All relevant data are stored in a central data pool on the basis of the classification and logical structure of a nuclear power station. Thus the data pool always reflects the current state of project development with no redundancy. The fact that each item is only present once in the database and all users have (at least read) access to it means that concurrent engineering is possible. The progress of the project is free of contradiction thanks to implicit workflow steps. Progress is supported by plausibility checks, including standards and guidelines and specific catalogues (eg for valves, pipe parts) which makes for greater efficiency and thus higher quality and lower costs.

Following the automatic transfer of alphanumeric and logical base data from the system circuit plans into the central data pool, additional engineering data are then added. These are not limited to purely technical data, additional logical associations are created (for example which electrical drive is allocated to which kind of power supply) and active design functionality, eg materials and dimension logic for determining pipe categories, supports the progress of the project.

In parallel to the generation of system plans and filling the central data pool during the engineering phase, the structures (such as buildings with rooms, walls with openings and conduits) are being created in the 3D-CAD plant model. The generation of plans (eg building overviews, pipe laying plans, cross sections, perspective views) makes a major contribution to cost reduction.

Pipes and all other plant parts (eg containers, pumps) are transferred from the central data pool together with their technical data and then planned into the rooms and linked to each other. Collision and consistency checks are provided, as are interfaces to external computation processes. Planning results, such as the location of components, are transferred back to the central data pool.

The result of the modelling activities is a realistic, 3-dimensional representation of the complete plant as planned. This in turn is the basis for animation and simulation applications, eg for virtual reality, which allows maintenance and repair procedures to be validated and optimised.

Design and documentation of the electrical systems

The designs of the electrical systems are based on primary data from the central data pool. These are modified as required and consumer and component data for the plant’s own electricity requirements are added. Further planning steps are the following:

• The electrical system processing (eg the allocation of users to switching gear, cable processing via stored cable selection tables, the processing of switching gear with the graphic connector assignments of the cabinets, branch processing with graphic branching plans).

One of the major tasks of construction technology is the orderly processing of the many loads to be taken into consideration, their combination, taking account of internal and external influences, and their graphic display using a 3-D building model. The regulations on superimposition and the more stringent requirements of the Eurocode lead to a large number of load case combinations. If, for example, there are only 10 loads in a detailed measurement, this produces 2n-1, ie 512 combinations, for which different safety coefficients must be applied. Rules for this complex task are implemented in an information system and the construction engineer can calculate and record the detailed measurements instead of making “valid assumptions based on his knowledge as an engineer” as previously. The combination of the 3-D representation with the items in the standard services list makes interior planning much easier and can be used as a direct basis for drawing up the invitation to tender.

Further tasks which can be carried out to support and facilitate scheduling are the static optimisation of individual components, the provision of information on the building materials used, links with the calculation of construction costs, with the processes of tendering, commissioning and implementation and the documentation of building procedures.

USING THE DP TOOL

A joint development of such a complex entity as the EPR, calls for a clear division of tasks and labour. On the other hand, however, efficient co-operation is only possible with joint tools and an organised exchange of data. Appropriate agreements were made to this effect as part of the basic design contract between the German and French associates. Special features, such as the need for two coding systems, the German KKS and France’s ECS, had to be taken into account when designing the DP tools.

Making extensive use of the tools described above, priority tasks were set for executing the basic design.

All system circuit plans were drawn up with the 2D-CAD program using a joint “mechanical symbol library”. Technical data and logical connections were generated in addition to the graphic representation and form the basis of the central data pool.

The central data pool was created by transferring the alphanumeric and logical CAD prime data; this was supplemented in the departments concerned by further technical data and logical connections, such as “electric drive belongs to supply category DC”.

In order to standardise building components, catalogues (eg a valve and pipe component catalogue) were specified between the parties and integrated into the central data pool. Allocation of plant objects to catalogue types led to the desired limitation to the defined types.

Materials and measurement logic, a procedure to ensure that technical requirements are met in the planning of pipe components, is an example of active project support. On the basis of the input values for the pipes (eg pipe diameter, type of material), a standard catalogue and the “Kesselformel” (boiler formula), this procedure was used to calculate automatically the appropriate pipe category, maximum bending radius, external diameter and the wall thickness of the pipes.

The basic design contract stipulated that the EPR engineering data be made available to the customers in the form of lists and data sheets. These lists (eg lists of component, valves, pipes) are output exclusively by the central data pool, always with up-to-date, consistent information. The central data pool also formed the basis for other statistical evaluations and the Bill of Quantities on which the cost calculations for the EPR are based.

The 3D-CAD program was used to model the construction structures for all the buildings of the Nuclear Island; all agreed plans and views were output in a time-saving manner as copies of the 3-D model.

When all the relevant pipe sections and components had been exported from the central data pool to the 3D-CAD model they were planned into the appropriate buildings and rooms.

Another aspect of active planning support was the pipe calculations which accompanied the planning of pipes for which safety was of particular importance. For this, the pipe route and the mounting points are shown in a finite element model and a check is made to ensure that the design data (support strengths) have been precisely observed.

Our partners in France are responsible for some of the electrical work for the EPR. For this too, all data on electricity consumers were exported from the central data pool and used as input for the engineering.

THE WAY AHEAD

The phases which will follow the basic design phase, the basic design optimisation phase (BDOP), detailed design, implementation, construction and start-up, will also require special tools. The necessary adjustments and extensions have been initiated; they are all based on the existing central data pool.

A major new feature for planning projects in the nuclear power station sector will be the possibility of visualisation of complex assembly processes and operational procedures such as moving fuel elements between the pool and the pressurised containers or simulated operational procedures such as repairs and maintenance work in areas of high radiation.

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